The field of the invention relates generally to electrical fuse devices and methods of manufacturing electrical fuses, and more specifically to dual-element, time-delay fuses and methods of manufacturing the same.
Fuses are widely used as overcurrent protection devices to prevent costly damage to electrical circuits. Fuse terminals typically form an electrical connection between an electrical power source or power supply and an electrical component or a combination of components arranged in an electrical circuit. One or more fusible links or elements, or a fuse element assembly, is connected between the fuse terminals, so that when electrical current flow through the fuse exceeds a predetermined limit, the fusible elements melt and open one or more circuits through the fuse to prevent electrical component damage.
So-called dual-element, time-delay fuses are known that include a high overcurrent fuse element and a low overcurrent fuse element inside a housing of the fuse. The low overcurrent fuse element includes a device, often referred to in the art as a fuse trigger, that will electrically open a circuit path through the low overcurrent fuse element during an overload condition after a specified amount of time. Such fuses are effective to prevent electrical overload conditions from passing to upstream fuses in an electrical power system that would otherwise not cause the high overcurrent fuse element to open, and facilitate selective coordination of overcurrent protection devices to ensure reliability of electrical power systems supplying power to vital loads.
Conventional designs for trigger devices in dual-element, time-delay fuses present a number of challenges from a manufacturing perspective, and improvements are desired.